Cumulus Media Chief Executive Lew Dickey and his brother, John Dickey, the No. 2 executive at the radio giant, stepped down from the Atlanta company on Tuesday following a board shake-up, several sources confirmed to The Post.

Mary G. Berner, the magazine executive who ran Reader’s Digest for five years, was quickly named chief — but not before Cumulus shares tumbled 8.3 percent, to 68.2 cents, down from 74.4 cents, just minutes after The Post reported the Dickeys’ ouster.

The 53-year-old radio veteran founded Cumulus in 1997 by acquiring Citadel Broadcasting and Dial Global. He ran it for nearly 19 years, building a small operation into a 460-station juggernaut in 90 US markets. Cumulus also owns Westwood One, which syndicates the shows of Mark Levin, Don Imus and John Batchelor.

But the company has had a rough 2015. It reported a nearly 18 percent decline in operating profits in the second quarter amid falling sales — and its stock has fallen 83 percent this year. While the entire radio sector has been hit hard, Cumulus has been hit the hardest.

On Sept. 15, Moody’s cut the ratings of Cumulus’ $2.4 billion of debt to B3 — which is junk status.

The news of the Dickeys’ departure was first reported by music blog Hits Daily Double. The blog suggests a huge reorganization of the company is on the way.

Dickey, who was named vice chairman of the board, was also president. His brother was executive vice president and ran programming.

The company shake-up was said to be initiated by Chairman Jeffrey Marcus, who is also a partner in Crestview Partners and owns a 27 percent stake in Cumulus.

Lew Dickey will leave his post as CEO on Oct. 13, and John will exit on that date as well.